Catheter with increased electrode density spine assembly having reinforced spine covers

ABSTRACT

An electrophysiology catheter with a distal electrode assembly having covered spine carrying a plurality of microelectrodes. The spines have nonconductive covers that are reinforced with tensile members, e.g., wires or fibers, that extend (or have portions that extend) longitudinally so as to minimize any elongation of the covers and the microelectrodes carried thereon. The tensile members may also have a length greater than the length of the spines so the proximal portions extend proximally from the spines, through the catheter and at least into the control handle for actuation by an operator for deflecting and moving the spines, like “fingers.”

FIELD OF INVENTION

This invention relates to an electrophysiology catheter, in particular,a cardiac electrophysiology catheter with an electrode configurationthat provides for more accurate and discrete sensing of fractionatedsignals.

BACKGROUND

Electrode catheters have been in common use in medical practice for manyyears. They are used to stimulate and map electrical activity in theheart and to ablate sites of aberrant electrical activity.

In use, the electrode catheter is inserted into a major vein or artery,e.g., femoral artery, and then guided into the chamber of the heartwhich is of concern. Once the catheter is positioned within the heart,the location of aberrant electrical activity within the heart is thenlocated.

One location technique involves an electrophysiological mappingprocedure whereby the electrical signals emanating from the conductiveendocardial tissues are systematically monitored and a map is created ofthose signals. By analyzing that map, the physician can identify theinterfering electrical pathway. A conventional method for mapping theelectrical signals from conductive heart tissue is to percutaneouslyintroduce an electrophysiology catheter (electrode catheter) havingmapping electrodes mounted on its distal extremity. The catheter ismaneuvered to place these electrodes in contact with the endocardium. Bymonitoring the electrical signals at the endocardium, aberrantconductive tissue sites responsible for the arrhythmia can bepinpointed.

For sensing by ring electrodes mounted on a catheter, lead wirestransmitting signals from the ring electrodes are electrically connectedto a suitable connector in the distal end of the catheter controlhandle, which is electrically connected to an ECG monitoring systemand/or a suitable 3-D electrophysiology (EP) mapping system, forexample, CARTO, CARTO XP or CARTO 3, available from Biosense Webster,Inc. of Irwindale, Calif.

Smaller and more closely-spaced electrode pairs allow for more accuratedetection of near-field potentials versus far-field signals, which canbe very important when trying to treat specific areas of the heart. Forexample, near-field pulmonary vein potentials are very small signalswhereas the atria, located very close to the pulmonary vein, providemuch larger signals. Accordingly, even when the catheter is placed inthe region of a pulmonary vein, it can be difficult for theelectrophysiologist to determine whether the signal is a small, closepotential (from the pulmonary vein) or a larger, farther potential (fromthe atria). Smaller and closely-spaced bipoles permit the physician tomore accurately remove far field signals and obtain a more accuratereading of electrical activity in the local tissue. Accordingly, byhaving smaller and closely-spaced electrodes, one is able to targetexactly the locations of myocardial tissue that have pulmonary veinpotentials and therefore allows the clinician to deliver therapy to thespecific tissue. Moreover, the smaller and closely-spaced electrodesallow the physician to determine the exact anatomical location of theostium/ostia by the electrical signal.

Increasing electrode density (for example, by increasing the pluralityof electrodes carried on the catheter) also improves detection accuracy.However, the more electrodes that are carried on the catheter,especially with higher electrode density, the risk of electrodestouching and shorting increases. Moreover, there is always the desire toimprove electrode tissue contact with highly-flexible electrode assemblystructures that can make contact reliably but in a manner whereby theelectrode-carrying structures behave in a controllable and predictablemanner without perforating or injuring tissue. As the materials used toconstruct these structures become more flexible and delicate, the riskof deformation and, in particular, elongation of the smaller ringelectrodes and their supporting structure during catheter assemblyincreases. Furthermore, as electrode assembly structures become moredelicate, the risk of components detaching, kinking and tanglingincreases.

Accordingly, a need exists for an electrophysiology catheter withclosely-spaced microelectrodes for high electrode density. There is alsoa need for an electrophysiology catheter having electrode-carryingstructures that are delicate in construction to provide desired flexibleyet be predictable in their movement upon tissue contact. There is afurther need for an electrophysiology catheter that is constructed in amanner that minimizes the risk of components detaching, kinking andtangling, and reinforces the spine construction to minimize deformation,including elongation of soft spine covers and of microelectrodes carriedthereon.

SUMMARY OF THE INVENTION

The present invention is directed to an electrophysiology catheter witha distal electrode assembly carrying very small and closely-spacedmicroelectrodes on a plurality of divergent spines that can flexiblyspread over tissue surface area for simultaneously detecting signals atmultiple locations with minimized detection of undesirable noise,including far-field signals. The distal electrode assembly is configuredto conform to different anatomies of tissue in the atrial cavities ofthe heart. The spines have curved segments or curved segments withlinear segments for a wide range of adaptability to different tissuesurfaces while providing mechanical advantages at distinct segments forimproved flexibility and rigidity to facilitate better tissue contact.Each spine has a generally tapering configuration from its proximal endto its distal end for providing a stronger, more rigid proximal base andmore flexible distal ends for improved flexibility characteristics whileminimizing the risk of spines touching or entangling.

In some embodiments, an electrophysiology catheter has an elongated bodyand a distal electrode assembly. The distal electrode assembly has aproximal stem, a plurality of spines emanating from the stem and aplurality of nonconductive spine covers, each surrounding a respectivespine, each spine cover having a plurality of tensile members embeddedin a sidewall of the cover.

In some embodiments, the tensile members extend in the longitudinaldirection.

In some embodiments, the tensile members have a portion extending in thelongitudinal direction.

In some embodiments, the tensile members include wires.

In some embodiments, tensile members include fibers.

In some embodiments, an electrophysiology catheter has an elongated bodyand a distal electrode assembly. The distal electrode assembly has aproximal stem and a plurality of spines, each spine having an enlargeddistal portion, the enlarged distal portion having a through-hole. Thedistal electrode assembly also has a plurality of nonconductive spinecovers, each surrounding a respective spine. The distal electrodeassembly further has a cap cover encapsulating the enlarged distalportion, the cap cover having a portion extending through thethrough-hole.

In some embodiments, an electrophysiology catheter has an elongated bodyand a distal electrode assembly. The distal electrode assembly has aproximal stem and a plurality of at least eight spines, each spinehaving a first section with a first preformed curvature defined by afirst radius, and a linear section. The distal electrode assembly alsohas a plurality of nonconductive spine covers and a plurality ofmicroelectrodes, with at least one microelectrode on each spine.

In some embodiments, each spine includes a second section with a secondpreformed curvature defined by a second radius different from the firstradius, the second section with the second preformed curvature beingdistal of the first section with the first preformed curvature.

In some embodiments, the first radius is smaller than the second radius.

In some embodiments, the second preformed curvature is opposite of thefirst preformed curvature.

In some embodiments, the second section with the second preformedcurvature is distal of the first section with the first preformedcurvature.

In some embodiments, t In some embodiments, the linear section isbetween the first section with the first preformed curvature and thesecond section with the second preformed curvature.

In some embodiments, the second section with the linear section isdistal of the second section with the second preformed curvature.

In some embodiments, each covered spine has an outer circumference lessthan 3 french.

In some embodiments, the outer circumference is about 2.6 french.

In some embodiments, an electrophysiology catheter has an elongatedbody, and a distal electrode assembly. The distal electrode assembly hasa proximal portion, and a plurality of spines, each spine having alinear taper with a wider proximal end and a narrower distal end. Thedistal electrode assembly also has a plurality of nonconductive spinecovers, each nonconductive spine cover surrounding a respective spine.

In some embodiments, the linear taper is continuous.

In some embodiments, the linear taper is noncontinuous.

In some embodiments, the noncontinuous linear taper includes an indentedportion with a width lesser than a width of a more proximal stem and awidth of a more distal portion.

In some embodiments, a spine has a hinge along a lateral edge configuredfor in-plane deflection of the spine.

In some embodiments, an electrophysiology catheter has an elongated bodyand a distal electrode assembly. The distal electrode assembly has aproximal stem, a plurality of at least eight spines, each spine having alinear taper with a wider proximal end and a narrower distal end. Thedistal electrode assembly also has a plurality of nonconductive spinecovers, each nonconductive cover surrounding a respective spine. Thedistal electrode assembly further has a plurality of microelectrodes,the plurality being at least about 48, each microelectrode having alength of about 480 μm.

In some embodiments, the microelectrodes on each spine are separated bya distance ranging between about 1 mm and 3 mm, as measured betweenleading edges of the microelectrodes.

In some embodiments, the distance is about 2 mm.

In some embodiments, the microelectrodes on each spine are arranged asbipole pairs, with leading edges of microelectrodes within a pairseparated by a first distance ranging between about 1 mm and 3 mm, andwith leading edges of leading microelectrodes between pairs separated bya second distance ranging between 1 mm and 6 mm.

In some embodiments, the first distance is about 2 mm and the seconddistance is about 6 mm.

In some embodiments, the plurality of microelectrodes equals about 64.

In some embodiments, the plurality of microelectrodes equals about 72.

In some embodiments, a first ring electrode is carried on the proximalstem of the distal electrode assembly, and a second and a third ringelectrodes carried on a distal portion of the elongated body.

In some embodiments, an electrophysiology catheter has an elongatedbody, and a distal electrode assembly. The distal electrode assembly hasa proximal stem defining a circumference around the longitudinal axis.The distal electrode assembly also has a plurality of spines emanatingfrom the proximal stem and diverging at their distal ends, the pluralityof spines alternating between first spines and second spines around thecircumference of the stem. The distal electrode assembly further has aplurality of nonconductive spine covers, each spine cover surrounding arespective spine, and a plurality of microelectrodes having a staggeredconfiguration on the first spines and the second spines, wherein a mostproximal microelectrode on each first spine is positioned at a greaterdistance from the proximal stem, and a most proximal electrode on eachsecond spine is positioned at a lesser distance from the proximal stem.

In some embodiments, the distal electrode assembly comprises at leastfour first spines and four second spines, and each spine carries eightmicroelectrodes.

In some embodiments, each microelectrode has a length of about 480 μm.

In some embodiments, the microelectrodes on each spine are separated bya distance ranging between about 1 mm and 3 mm, as measured betweenleading edges of the microelectrodes.

In some embodiments, the distance is about 2 mm.

In some embodiments, the microelectrodes on each spine are arranged asbipole pairs, with leading edges of microelectrodes within a pairseparated by a first distance ranging between about 1 mm and 3 mm, andwith leading edges of leading microelectrodes between pairs separated bya second distance ranging between 1 mm and 6 mm.

In some embodiments, the first distance is about 2 mm and the seconddistance is about 6 mm.

In some embodiments, an electrophysiology catheter has an elongated bodyand a distal electrode assembly. The distal electrode assembly has aproximal stem having a side wall having an inner surface defining alumen, the side wall having an opening. The distal electrode assemblyalso has a plurality of spines emanating from the proximal stem anddiverging at their distal ends, and a plurality of nonconductive cover,each nonconductive cover surrounding a respective spine. The distalelectrode assembly further has a plurality of microelectrodes on eachspine, and a housing insert received in the lumen of the stem, thehousing insert having an outer surface leaving a void between the outersurface and the inner surface of the stem. An adhesive fills the voidbetween the inner surface of the proximal stem and the outer surface ofthe housing insert, the adhesive having a portion passing through theopening in the sidewall of the proximal stem.

In some embodiments, the adhesive has a second layer coating an outersurface of the stem and sealing the opening in the sidewall of theproximal stem.

In some embodiments, the housing insert has a lumen with a cross-sectionhaving an elongated kidney bean-shaped configuration.

In some embodiments, the housing insert has a lumen with a cross-sectionhaving a C-shaped configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings. It isunderstood that selected structures and features have not been shown incertain drawings so as to provide better viewing of the remainingstructures and features.

FIG. 1 is a perspective view of a catheter of the present invention,according to one embodiment.

FIG. 2 is an end cross-sectional view of a catheter body of the catheterof FIG. 1.

FIG. 3 is an end cross-sectional view of a deflection section of thecatheter of FIG. 1

FIG. 4 is a perspective view of a unibody support member, according toone embodiment.

FIG. 5A is a side view of a unibody support member, according to oneembodiment.

FIG. 5B is a detailed view of the unibody support member of FIG. 5A.

FIG. 5C is an end cross-sectional view of the unibody support member ofFIG. 5A, taken a line C-C.

FIG. 5D is a detailed view of an enlarged distal portion of a spine ofFIG. 5A.

FIG. 5E is a detailed view of an end cross-sectional view of a spine ofFIG. 5A.

FIG. 6A is a side view of a unibody support member, according to oneembodiment.

FIG. 6B is a detailed view of the unibody support member of FIG. 6A.

FIG. 6C is a detailed view of a distal portion of the spine of FIG. 6B.

FIG. 6D is a detailed view of an enlarged distal portion of a spine ofFIG. 6A.

FIG. 6E is an end cross-sectional view of the unibody support member ofFIG. 6B, taken along line E-E.

FIG. 6F is a detailed view of an end cross-sectional view of a proximalportion of the spine of FIG. 6B.

FIG. 6G is a detailed view of an end cross-sectional view of a distalportion of the spine of FIG. 6B.

FIG. 7A is a side view of a unibody support member, according to oneembodiment.

FIG. 7B is a side view of the unibody support member of FIG. 7A, intissue contact.

FIG. 8A is a side view of a unibody support member, according to anotherembodiment.

FIG. 8B is a side view of the unibody support member of FIG. 8A, intissue contact.

FIG. 9A is a side view of a unibody support member, according to yetanother embodiment.

FIG. 9B is a side view of the unibody support member of FIG. 9A, intissue contact.

FIG. 10 is a side view of a unibody support member, according to oneembodiment, illustrated to show different parameters.

FIG. 11A is a top plan view of a spine with hinge formations, accordingto one embodiment.

FIG. 11B is a top plan view of a spine with hinge formations, accordingto another embodiment.

FIG. 12A is a side view of a covered spine, according to one embodiment,

FIG. 12B is a side view of a covered spine, according to anotherembodiment.

FIG. 13 is a front view of a distal electrode assembly, according to oneembodiment.

FIG. 14A is a side cross-sectional view of a junction between adeflection section and a distal electrode assembly, according to oneembodiment.

FIG. 14B is an end cross-sectional view of a housing insert of FIG. 14A.

FIG. 15A is a side cross-sectional view of a junction between adeflection section and a distal electrode assembly, according to anotherembodiment.

FIG. 15B is an end cross-sectional view of a housing insert of FIG. 15A.

FIG. 16 is a side perspective view of a covered spine with reinforcingtensile members, according to one embodiment.

FIG. 17 is a detailed side cross-sectional view of a portion of ajunction with reinforcing tensile members, according to one embodiment.

FIG. 18 is an end cross-sectional view of a housing insert withreinforcing tensile members passing therethrough, according to oneembodiment.

FIG. 19. is an end cross-sectional view of a deflection section withreinforcing tensile members passing therethrough, according to oneembodiment.

FIG. 20 is an end cross-sectional view of a catheter body withreinforcing tensile members passing therethrough, according to oneembodiment.

FIG. 21 is a schematic illustration of a heart and placement of thecatheter of the present invention for tissue contact, according variousembodiments.

FIG. 22 is a schematic illustration of a distal electrode assembly incontact with tissue in a pulmonary vein, according to one embodiment.

FIG. 23 is a schematic illustration of a distal electrode assembly incontact with tissue of a lateral wall of the heart, according to oneembodiment.

FIG. 24 is a schematic illustration of a distal electrode assembly incontact with tissue of an inferior wall or apex of the heart, accordingto one embodiment.

FIG. 25 is an end cross-sectional view of the distal end of the distalelectrode assembly of FIG. 15A, taken along line A-A.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, in some embodiments of present invention, acatheter 10 includes a catheter body 12, an intermediate deflectionsection 14, a distal electrode assembly 15, and a control handle 16proximal of the catheter body 12. The distal electrode assembly 15includes a plurality of spines 17, with each spine supporting aplurality of microelectrodes 18.

In some embodiments, the catheter body 12 comprises an elongated tubularconstruction, having a single, axial or central lumen 19, as shown inFIG. 2. The catheter body 12 is flexible, i.e., bendable, butsubstantially non-compressible along its length. The catheter body 12can be of any suitable construction and made of any suitable material. Apresently preferred construction comprises an outer wall 20 made of apolyurethane, or PEBAX. The outer wall 20 comprises an imbedded braidedmesh of high-strength steel, stainless steel or the like to increasetorsional stiffness of the catheter body 12 so that, when the controlhandle 16 is rotated, the deflection section 14 of the catheter 10rotates in a corresponding manner.

The outer diameter of the catheter body 12 is not critical. Likewise thethickness of the outer wall 20 is not critical, but is thin enough sothat the central lumen 19 can accommodate components, including, forexample, one or more puller wires, electrode lead wires, irrigationtubing, and any other wires and/or cables. In some embodiments, theinner surface of the outer wall 20 is lined with a stiffening tube 21,which can be made of any suitable material, such as polyimide or nylon.The stiffening tube 21, along with the braided outer wall 20, providesimproved torsional stability while at the same time minimizing the wallthickness of the catheter, thus maximizing the diameter of the centrallumen 19. As would be recognized by one skilled in the art, the catheterbody construction can be modified as desired. For example, thestiffening tube can be eliminated.

In some embodiments, the intermediate deflection section comprises ashorter section of tubing 30, which as shown in FIG. 3, has multiplelumens 31. In some embodiments, the tubing 30 is made of a suitablebiocompatible material more flexible than the catheter body 12. Asuitable material for the tubing 19 is braided polyurethane, i.e.,polyurethane with an embedded mesh of braided high-strength steel,stainless steel or the like. The outer diameter of the deflectionsection 14 is similar to that of the catheter body 12. The plurality andsize of the lumens are not critical and can vary depending on thespecific application.

Various components extend through the catheter 10. In some embodiments,the components include lead wires 22 for the distal electrode assembly15, one or more puller wires 23A and 23B for deflecting the deflectionsection 14, a cable 24 for an electromagnetic position sensor 26 (seeFIG. 14A and FIG. 15A) housed at or near a distal end of the deflectionsection 14. In some embodiments, the catheter includes an irrigationtubing 27 for passing fluid to the distal end of the deflection section14. These components pass through the central lumen 19 of the catheterbody 12, as shown in FIG. 2.

In the deflection section 14, different components pass throughdifferent lumens 31 of the tubing 30 as shown in FIG. 3. In someembodiments, the lead wires 22 pass through one or more lumens 31A, thefirst puller wire 23A passes through lumen 31B, the cable 24 passesthrough lumen 31C, the second puller 23B passes through lumen 31D, andthe irrigation tubing 27 passes through lumen 31E. The lumens 31B and31D are diametrically opposite of each other to provide bi-directionaldeflection of the intermediate deflection section 14. Additionalcomponents can pass through additional lumens or share a lumen with theother aforementioned components, as needed.

Distal of the deflection section 14 is the distal electrode assembly 15which includes a unibody support member 40 as shown in FIG. 4. In someembodiments, the unibody support member 40 comprises a superelasticmaterial having shape-memory, i.e., that can be temporarily straightenedor bent out of its original shape upon exertion of a force and iscapable of substantially returning to its original shape in the absenceor removal of the force. One suitable material for the support member isa nickel/titanium alloy. Such alloys typically comprise about 55% nickeland 45% titanium, but may comprise from about 54% to about 57% nickelwith the balance being titanium. A nickel/titanium alloy is nitinol,which has excellent shape memory, together with ductility, strength,corrosion resistance, electrical resistivity and temperature stability.

In some embodiments, the member 40 is constructed and shaped from anelongated hollow cylindrical member, for example, with portions cut(e.g., by laser cutting) or otherwise removed, to form a proximalportion or stem 42 and the elongated bodies of the spines 17 whichemanate from the stem longitudinally and span outwardly from the stem.The stem 42 defines a lumen 43 therethrough for receiving a distal endportion 30D of the multi-lumened tubing 30 (see FIG. 14A) of thedeflection section 14, and various components, as further discussedbelow, which are either housed in the stem 42 or extend through thelumen 43.

Each spine 17 of the member 40 has an enlarged distal portion 46, andeach spine has a wider proximal end and a narrower distal end. In someembodiments, as shown in FIG. 5A, FIG. 5B, FIG. 5C, FIG. 5D and FIG. 5E,the spine is linearly tapered for “out-of-plane” flexibility that variesalong it length (see arrows A1 in FIG. 5E), including flexibility thatincreases toward the distal end 48. In some embodiment, one or morespines 17 have a proximal portion 17P with a uniform width W1, a distalportion 17D1 with continuous linear taper defined by taper lines T1 (seeFIG. 5B), and a more distal portion 17D2 with a uniform width W2<W1. Thedistal portions 17D1 had a continuously gradual increase in flexibilityso that the spines can adopt a predetermined form or curvature when thedistal portions 46 come into contact with tissue. The resulting spineswith a relatively more rigid proximal portion and a relatively moreflexible distal portion help prevent the spines from crossing andoverlapping each other during use.

In some embodiments, one or more spines 17 have a noncontinuous lineartaper between the ends 41 and 46, as shown in FIG. 6A, FIG. 6B, FIG. 6C,FIG. 6D, FIG. 6E, FIG. 6F and FIG. 6G. The noncontinuous linear taperincludes one or more narrower or indented portions 50 that arestrategically positioned along the spine to interrupt an otherwisecontinuous linear taper, defined by taper T2 between the stem 42 and theenlarged distal portion 46. Each indented portion 50 has a width W (seeFIG. 6C) that is lesser than the width WD of a more distal portion andalso lesser than the width WP of a more proximal portion where widthWD<width WP. Each indented portion 50 thus advantageously allows thatregion of the spine to have a different flexibility than immediatelyadjacent (distal and proximal) portions 51 of the spine, and to providea degree of independent flexibility between the portions separated bythe indented portion 50 (see FIG. 6B). Accordingly, these spines areallowed to exhibit markedly greater flexibility and hence tighter ormore acute curvatures in the region of the indented portions 50 relativeto the portions 51 of the spines when the distal portions 46 come intocontact with tissue.

In some embodiments, each spine (between the distal end of the stem 42and the distal end of the spine) has a length ranging between about 1.0cm to 2.5 cm, or between about 1.50 cm and 2.0 cm, a width rangingbetween about 0.009 inches and 0.02 inches. In some embodiments, theindented portion 50 has a length ranging between about 10%-20% of thelength of the spine, and a width W ranging between about 50%-80% ofimmediately adjacent widths, with its leading proximal edge located atabout 55%-65% of the length of the spine, measured from the distal endof stem 42.

To further facilitate microelectrode contract with tissue along theentire length of the spine, each spine 17 has a preformed configurationor curvature, accomplished by, for example, heat and a molding fixture.One or more spines 17 have at least two different preformed curvaturesC1 and C2, as shown in FIG. 7A, with segment S1 with preformed curvatureC1 defined by radius R1 and segment S2 with preformed curvature C2defined by radius R2, wherein radius R1<R2 and the curvatures C1 and C2are generally in opposition direction of each other so that the spinesof the unibody support member 40 has a generally forward-facingconcavity that resembles an open umbrella. As shown in FIG. 7B (withonly two spines shown for purposes of clarity), when the spine distalends come in contact with an illustrative surface SF, the preformedspines transition from their neutral configuration N (shown in brokenlines) into their adaptive or temporarily “deformed” configuration Awhich may include a “crouched” profile (compared to their neutralconfiguration) that may be better suited for a region of heart tissuewith undulations. Advantageously, the unibody support member 40maintains its generally forward-facing concave configuration withoutturning inside out upon tissue contact, like an umbrella upturning instrong wind.

In some embodiments, one or more spines 17 have at least a curvedsegment and a linear segment. In some embodiments, one or more spineshave at least two different preformed curvatures along its length. Forexample, as shown in FIG. 8A, one or more spines 17 have a first segmentSA with preformed curvature CA defined by radius RA, a second segment SBwith preformed curvature CB defined by radius RB, and a third segment SCthat is linear, wherein radius RA<radius RB. As shown in FIG. 8B (withonly two spines shown for purposes of clarity), when the spine distalends come in contact with an illustrative surface SF, the preformedspines transition from their neutral configuration N into their adaptiveor temporarily “deformed” configuration A which may include a deeperconcavity (compared to their neutral configuration) that may be bettersuited for a region of heart tissue with a convexity.

As another example, as shown in FIG. 9A, one or spines 17D have a firstsegment SJ with preformed curvature CJ defined by radius RJ, a secondsegment SK that is linear, and a third segment SL with preformedcurvature CL defined by radius RL, wherein radius RJ<radius RL. As shownin FIG. 9B (with only two spines shown for purposes of clarity), whenthe spine distal ends come in contact with an illustrative surface SF,the preformed spines transition from their neutral configuration N intotheir adaptive or temporarily “deformed” configuration A which mayinclude a lower profile (compared to their neutral configuration) thatmay be better suited for a flatter region of heart tissue.

With reference to FIG. 10, in some embodiments, the unibody supportmember 40 and its spines 17 can be defined by a plurality of parameters,including the following, for example:

a=height of second curvature, ranging between about 0.00″ and 0.050″

b=distal length of second curvature, ranging between about 0.302″ and0.694″

c=proximal length of second curvature, ranging between about 0.00″ and0.302″

d=distance between first and second curvature, ranging between about0.00″ and 0.170″

e=radius of first curvature, ranging between about 0.075″ and 0.100″

f=length of uniform width segment, being about 0.100″

g=concavity depth, ranging between about 0.123″ and 0.590″

Notably, in some embodiments of the unibody support member 40, theproximal (or first) preformed curvature is opposite of the distal (orsecond) preformed curvature so the spines 17 of the distal electrodeassembly 15 can maintain its general concavity and remain forward-facingupon tissue contact, without inverting, while the highly-flexible spinesallow the assembly to have a pliability or “give” that prevents thedistal tips of the spines from perforating or otherwise causing damageto tissue upon contact and when the distal electrode assembly is pressedtoward the tissue surface to ensure tissue contact by each of the spines17. Moreover, in some embodiments, the indented portion 50 may spanbetween the proximal and distal preformed curvatures so that each ofthree portions (proximal, indented and distal) of the spines can behavedifferently and have a degree of independence in flexibility of eachother in response to tissue contact and the associated pressures appliedby the operator user of the catheter.

It is understood that the foregoing figures illustrate exaggerateddeformities and curvatures of the spines for ease of discussion andexplanation, whereas actual deformities and curvatures may be much moresubtle and less acute.

In some embodiments, one or more spines 17 are also configured with ahinge 90 for in-plane (side-to-side) deflection. As shown in FIG. 11Aand FIG. 11B, a spine 17 can have a plurality of notches or recessesalong opposing lateral edges, including expandable recess 80 (e.g., inthe form of slits 81 and circular openings 82) along one edge 85 a andcompressible recess 83 (e.g., in the form of slots 84 and circularopenings 82) along an opposite edge 85 b, forming a hinge 90 for morein-plane deflection along those edges. In the embodiments of FIG. 11Aand FIG. 11B, uni-deflection occurs toward the edge 85 b of the spine17. However, it is understood that where compressible recess 83 areformed along both the edges 85 a and 85 b the spine 17 hasbi-directional deflection toward either edge 85 a or 85 b. Suitablehinges are described in U.S. Pat. No. 7,276,062, the entire content ofwhich is incorporated herein by reference.

As shown in FIG. 12A and FIG. 12B, each spine 17 of the distal electrodeassembly 15 is surrounded along its length by a non-conductive spinecover or tubing 28. In some embodiments, the non-conductive spine cover28 comprises a very soft and highly flexible biocompatible plastic, suchas PEBAX or PELLATHANE, and the spine cover 28 is mounted on the spinewith a length that is coextensive with the spine as between the stem 42and the the enlarged distal portion 46. A suitable construction materialof the spine cover 28 is sufficiently soft and flexible so as generallynot to interfere with the flexibility of the spines 17.

In some embodiments, each covered spine 17 along its length has adiameter D of less than 3 french, preferably a diameter of less than 2.7french, and more preferably a diameter of 2 french, (e.g., between about0.025″ and 0.035″ in diameter).

Each spine 17 at includes an atraumatic distal cover or cap 45 (see FIG.12A) encapsulating the enlarged distal portion 46. In some embodiments,the cover 45 comprises an biocompatible adhesive or sealant, such aspolyurethane, which has a bulbous configuration to minimize injury totissue upon contact or the application of pressure against tissue. Theformation of the cover 45 includes a bridging portion 63 of the adhesiveor sealant that passes through the through-hole 47 in the enlargeddistal portion 46 and advantageously creates a mechanical lock thatsecures the cover 45 on the distal portion 46 and minimizes the risk ofthe cover 45 detaching from the enlarged distal portion 46.

Each spine 17 carries a plurality of microelectrodes 18. The pluralityand arrangement of microelectrodes can vary depending on the intendeduse. In some embodiments, the plurality ranges between about 48 and 72,although it is understood that the plurality may be greater or lesser.In some embodiments, each microelectrode has a length L of less than 800μm, for example, ranging between about 600 μm and 300 μm, and, forexample, measuring about 480 μm, 460 μm or about 450 μm. In someembodiment, the distal electrode assembly 15 has an area coveragegreater than about 7.1/cm², for example, ranging between about 7.2/cm²and 12.6/cm². In some embodiments, the distal electrode assembly 15 hasa microelectrode density greater than about 2.5 microelectrodes/cm², forexample, ranging between about 4 microelectrodes/cm² and 7microelectrodes/cm².

In some embodiments, the distal electrode assembly 15 has eight spines,each of about 1.5 cm in length and carrying eight microelectrodes for atotal of 48 microelectrodes, each with microelectrode having a length ofabout 460 μm, wherein the assembly 15 has an area coverage of about7.1/cm², and a microelectrode density of about 7 microelectrodes/cm².

In some embodiments, the distal electrode assembly 15 has eight spines,each of about 2.0 cm in length and carrying six microelectrodes for atotal of 48 microelectrodes, each with microelectrode having a length ofabout 460 μm, wherein the assembly 15 has an area coverage of about12.6/cm², and a microelectrode density of about 4 microelectrodes/cm².

The microelectrodes 18 on a spine 17 may be arranged with a variety ofspacing between them as either monopoles or bipoles, with the spacingmeasured as the separation between respective leading edges of adjacentmicroelectrodes or microelectrode pairs. As monopoles, themicroelectrodes 18 can be separated by a distance S1 ranging betweenabout 1 mm and 3 mm, with reference to FIG. 12A. As bipoles, adjacentpairs of microelectrodes 18 can be separated by a distance S2 rangingbetween 1 mm and 6 mm, with reference to FIG. 12B.

In some embodiments, six microelectrodes are arranged as three bipolepairs, with a spacing S1 of 2.0 mm between proximal edges of a bipolepair, and a spacing S2 of 6.0 mm between proximal edges of adjacentbipole pairs, with reference to FIG. 12B, which may be referred togenerally as a “2-6-2” configuration. Another configuration, referred toas a “2-5-2-5-2” configuration, has three bipole pairs, with a spacingS1 of 2.0 mm between proximal edges of a bipole pair, and a spacing S2of 5.0 mm between proximal edges of adjacent bipole pairs.

In some embodiments, six microelectrodes are arranged as monopoles, witha spacing S1 of 2.0 mm between proximal edges of adjacent monopoles,with reference to FIG. 12A. which may be referred to as “2-2-2-2-2”configuration. In some embodiments, the space S1 is about 3.0 mm andthus is referred to as a “3-3-3-3-3” configuration.

In some embodiments, the most proximal microelectrode 18P of each spineis carried on the spine at a different location from the most proximalmicroelectrode 18P of adjacent spines. As illustrated in FIG. 13,whereas the spacing between microelectrodes on any one spine may beuniform throughout the distal electrode assembly, the microelectrodesalong any one spine is staggered relative to the microelectrodes alongadjacent spines. For example, the distance D1 between the most proximalmicroelectrode 18P and the end of the stem 42 for spines 17A, 17C, 17Eand 17G is greater than the distance D2 between the most proximalelectrodes 18P and the end of the stem 42 for spines 17B, 17D, 17G and17G. This staggered configuration minimizes the risk of microelectrodeson adjacent spines from touching and shorting, especially when anoperator sweeps the distal electrode assembly against tissue.

Components of construction and assembly of the junction between thedistal electrode assembly and the distal end portion of the deflectionsection 14 are described in U.S. Pat. Nos. 7,089,045, 7,155,270,7,228,164, and 7,302,285, the entire disclosures of which areincorporated herein by reference. As shown in FIG. 14A, the stem 42 ofthe unibody support member 40 receives a narrowed distal end 30D of themulti-lumened tubing 30 of the deflection section 14. Surrounding thestem 42 circumferentially is a nonconductive sleeve 68 that iscoextensive with the stem between its proximal end and its distal end.Distal end 68D of the sleeve 68 extends over the proximal ends 28P ofthe nonconductive spine tubings 28 so as to help secure the tubings 28on the spines 17.

Proximal of the distal end 30D is a housing insert 60 that is alsoreceived and positioned in the lumen 43 of the stem 42 of the unibodysupport member 40. The housing insert 60 has a length in thelongitudinal direction that is shorter than the length of the stem 42 sothat it does not protrude past the distal end of the stem 42. Thehousing insert 60 is configured with one or more lumens. One lumen 71may have a noncircular cross-section, for example, a cross-section thatgenerally resembles a “C” or an elongated kidney-bean, and another lumen72 may have a circular cross-section, as shown in FIG. 14B, so that thelumens can nest with each other to maximize the size of the lumens andincrease space efficiency within the housing insert 60. Componentspassing through the more lumen 71 are not trapped in any one location orposition and thus have more freedom to move and less risk of breakage,especially when segments of the catheter are torqued and components aretwisted.

In some embodiments, the electromagnetic position sensor 26 (at thedistal end of the cable 24) is received in the lumen 72. Othercomponents including, for example, the irrigation tubing 27, and thelead wires 22 for the microelectrodes 18 on the distal electrodeassembly 15 (and lead wires 25 for any ring electrodes 67, 69, and 70proximal of the spines 17) pass through the lumen 71. In that regard,the housing insert 60 serves multiple functions, including aligning andpositioning the various components within the stem 42 of the unibodysupport member 40, provides spacing for and separation between thesevarious components, and serves as a mechanical lock that reinforces thejunction between the distal end of the deflection section 14 and thedistal electrode assembly 15. In the latter regard, the junction, duringthe assembly and use of the catheter, can be subject to a variety offorces that can torque or pull on the junction. Torque forces, forexample, can pinch the irrigation tubing 27 to impede flow, or causebreakage of the lead wires 22 and 25. To that end, the junction isadvantageously assembled in a configuration with the housing insert 60to form a mechanical lock, as explained below.

The housing insert 60 may be selectively configured with an outerdiameter that smaller than the inner circumference of the lumen 43 ofthe stem 42 by a predetermined amount. This creates an appreciable voidin the lumen 43 that is filled with a suitable adhesive 61, such aspolyurethane, to securely affix the housing insert 60 inside the lumen43 and to the distal end of the multi-lumened tubing 30 so as tominimize, if not prevent, relative movement between the insert 60 andthe stem 42. The housing insert 60 protects the components it surrounds,including the electromagnetic position sensor 26 (and its attachment tothe cable 24), the irrigation tubing 27, and the lead wires 22 and 25,and provides a larger and more rigid structure to which the stem 42 isattached. To that end, the housing insert 60 may even have anoncircular/polygonal outer cross-section and/or a textured surface toimprove the affixation between the housing insert 60 and the adhesive61.

To facilitate the application of the adhesive into the void, the stem 42is formed with an opening 65 in its side wall at a location that allowsvisual and mechanical access to the housing insert 60 after it has beeninserted into the lumen 43 of the stem 42. Visual inspection of thelumen 43 and components therein during assembly of the junction isprovided through the opening 65. Whereas any adhesive applied to theouter surface of the housing insert 60 before insertion into the lumen43 may squirt out of the stem 42 during insertion, additional adhesivemay be advantageously applied into the lumen 43 through the opening 65to fill the void and thus securely affix the housing insert 60 to thestem 42 and the distal end portion of the multi-lumened tubing 30. Thecombination of the housing insert 60 and its spatially-accommodatinglumen 71 provides a more integrated and less vulnerable junction betweenthe distal electrode assembly 15 and the deflection section 14.

In some embodiments, the catheter 10 includes the irrigation tubing 27whose distal end 27D is generally coextensive with the distal end of thestem 42 of the unibody support member 40. As such, irrigation fluid,e.g., saline, is delivered to the distal electrode assembly 15 from aremote fluid source that provides irrigation fluid via a luer hub 100(FIG. 1) via the irrigation tubing 27 that extends through the controlhandle 16, the center lumen 19 of the catheter body 12 (FIG. 2), and thelumen 31E of the tubing 30 of the deflection section 14 (FIG. 3), whereit exits the distal end of the irrigation tubing 27 at the distal end ofthe stem 42 of the unibody support member 40, as shown in FIG. 15A andFIG. 25. A suitable adhesive 90, such as polyurethane, plugs and sealsthe lumen 43 around the distal end of the irrigation tubing 27. In someembodiments, the catheter is without irrigation and the distal end ofthe stem 42 of the unibody support member 40 is sealed in its entiretyby the adhesive or sealant 90, such as polyurethane, as shown in FIG.14A.

FIG. 16 illustrates an embodiment wherein the nonconductive spinetubings 28 include reinforcing tensile members 53. As understood by oneof ordinary skill in the art, the microelectrodes 18 are mounted on thespine cover or tubing 28 wherein an elongated tubular mandrel (notshown) is positioned in the lumen of the spine cover 28 to support themicroelectrodes 18 while they are rotationally swaged onto the spinecover 28. The microelectrodes 18 may have a circular cross-section,including the configuration of a circle or an oval. To prevent or atleast minimize undesirable deformation of the microelectrodes 18 and thespine cover 28 during swaging, including elongation in the longitudinaldirection, the spine cover 28 on which the microelectrodes are carriedand swaged onto includes reinforcing tensile members 53, as shown inFIG. 16. Tensile members 53, for example, wires or fibers (usedinterchangeably herein), are embedded (for example, during extrusion ofthe tensile members) in the side wall 54 of the tubing. The tensilemembers 53 may be embedded in the nonconductive cover extrusion in auniaxial or braided pattern, extending in the longitudinal direction orat least having portions extending in the longitudinal direction. Assuch, the tensile members serve to resist undesirable elongation ofparticularly soft and flexible spine cover 28 and the microelecrodes 18in the longitudinal direction. Examples of suitable tensile membersinclude VECTRAN, DACRON, KEVLAR or other materials with low elongationproperties. The plurality of the reinforcing tensile members is notcritical. In some embodiments, the plurality may range between two andsix that are arranged in an equi-radial configuration. In theillustrated embodiment, the spine cover 28 includes four tensile membersat 0, 90, 180 and 270 degrees about the side wall 54.

In some embodiments, distal ends of the tensile members 53 are anchoredin the bulbous cover 45 encapsulating the enlarged distal portion of thespines 17 and/or rings 99D, as shown in FIG. 16, maybe compressed orclamped on over the spine cover 28 and spine 17. In some embodiments,proximal ends of the tensile members 53 are coextensive with theproximal end of the spine cover 28, and may also be anchored by rings99P (see FIG. 14A and FIG. 15A).

In some embodiments, the tensile members 53 have a much greater length.With reference to FIG. 17, FIG. 18, FIG. 19 and FIG. 20, the tensilemembers 53 extend through openings 44 formed in the stem 42 of theunibody support member 40 and into the lumen 43 of the stem 42. Thetensile members 53 then extend through the lumen 71 of the housinginsert 60, a lumen 31F of the tubing 30 of the deflection section 14,and the center lumen 19 of the catheter body 12, and into the controlhandle 16. Proximal ends of the tensile members 53 are configured formanipulation by an operator to deflect the spines 17 of the distalelectrode assembly 15 so they can individually function as “fingers.” Inthat regard, the tensile members may be formed in the side wall of thetubing 28 in a manner that allows longitudinal movement relative to thetubing 28 so that any one or more tensile members can be drawnproximally to bend or deflect the respective spine toward the side alongwhich those tensile members extend. As such, an operator is able tomanipulate one or more spines for individual deflection as needed ordesired, including when the distal electrode assembly is in contact withan uneven tissue surface where one or more spines need adjustment forbetter tissue contact.

With reference to FIG. 21, FIG. 22, FIG. 23 and FIG. 24, the catheter 10of the present invention is shown in use in all four chambers of theheart, namely, the left and right atria and the left and rightventricles, with the spines of the distal electrode assembly 15 readilyadapting and conforming to various contours and surfaces of the hearttissue anatomy, including, for example, inside a pulmonary vein, and onthe posterior wall of the right atrium, and the anterior, inferiorand/or lateral walls of the left and right ventricles, and the apex. Thepreformed configurations of the spines advantageously facilitate contactbetween the microelectrodes carried on the spines and tissue regardlessof the anatomy of the surface.

In some embodiments, the catheter 10 has a plurality of ring electrodesproximal of the distal electrode assembly 15. In addition to the ringelectrode 67, as shown in FIG. 1, the catheter carries another ringelectrode 69 more proximal than the ring electrode 67, and another ringelectrode 70 more proximal than the ring electrode 69. Lead wires 25 areprovided for these ring electrodes. In some embodiments, the ringelectrode 69 is located near the distal end 30D of the multi-lumenedtubing 30 of the deflection section 14, and ring electrode 70 isseparated from the ring electrode 69 by a distance S ranging betweenabout 1 mm and 3 mm. A respective lead wire 25 is connected to the ringelectrode 67 via opening 75 formed in the stem 42 of the unibody supportmember 40, and in the sleeve 68. Respective lead wires 25 for ringelectrodes 69 and 70 are connected to via openings (not shown) formed inthese side wall of the tubing 30 of the deflection section 14.

Each portion of the puller wires 23A and 23B extending through thecatheter body 12 is circumferentially surrounded by a respectivecompression coils 101A and 101B as understood in the art. Each portionof the puller wires 23A and 23B extending through the multi-lumenedtubing 30 of the deflection section is circumferentially surrounded by asheath that protects the puller wires from cutting into the tubing whenthe puller wires are deflected. Distal ends of the puller wires may beanchored in the sidewall of the tubing 30 at or near the distal end ofthe tubing 30, as understood in the art. Proximal ends of the pullerwires are anchored in the control handle 16 for actuation by theoperator of the catheter, as understood in the art.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. Any feature or structure disclosed in one embodiment maybe incorporated in lieu of or in addition to other features of any otherembodiments, as needed or appropriate. As understood by one of ordinaryskill in the art, the drawings are not necessarily to scale.Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

What is claimed is:
 1. An electrophysiology catheter comprising: anelongated body; a distal electrode assembly comprising: a proximal stem;a plurality of spines emanating from the stem; and a plurality ofnonconductive spine covers, each surrounding a respective spine, eachspine cover having a plurality of tensile members embedded in a sidewallof the spine cover.
 2. The catheter of claim 1, wherein the tensilemembers extend in the longitudinal direction.
 3. The catheter of claim1, wherein the tensile members have a portion extending in thelongitudinal direction.
 4. The catheter of claim 1, wherein the tensilemembers include wires.
 5. The catheter of claim 1, wherein the tensilemembers include fibers.
 6. An electrophysiology catheter comprising: anelongated body; a distal electrode assembly comprising: a proximal stem;a plurality of at least eight spines; a plurality of nonconductive spinecovers, each spine cover surrounding a respective spine and having atleast one tensile member; a plurality of microelectrodes, the pluralitybeing at least about 48, each microelectrode having a length of about480 μm.
 7. The catheter of claim 6, wherein the microelectrodes on eachspine are separated by a distance ranging between about 1 mm and 3 mm,as measured between leading edges of the microelectrodes.
 8. Thecatheter of claim 6, wherein the distance is about 2 mm.
 9. The catheterof claim 6, wherein the microelectrodes on each spine are arranged asbipole pairs, with leading edges of microelectrodes within a pairseparated by a first distance ranging between about 1 mm and 3 mm, andwith leading edges of leading microelectrodes between pairs separated bya second distance ranging between 1 mm and 6 mm.
 10. The catheter ofclaim 9, wherein the first distance is about 2 mm and the seconddistance is about 6 mm.
 11. The catheter of claim 6, wherein theplurality of microelectrodes equals about
 64. 12. The catheter of claim6, wherein the plurality of microelectrodes equals about
 72. 13. Thecatheter of claim 6, further comprising: a first ring electrode carriedon the proximal stem of the distal electrode assembly; and a second anda third ring electrodes carried on a distal portion of the elongatedbody.
 14. The catheter of claim 6, wherein each microelectrode has alength ranging between about 300 μm and 500 μm.
 15. The catheter ofclaim 6, wherein the microelectrodes on each spine are separated by adistance ranging between about 1 mm and 3 mm, as measured betweenleading edges of the microelectrodes.
 16. The catheter of claim 15,wherein the distance is about 2 mm.
 17. The catheter of claim 6, whereinthe microelectrodes on each spine are arranged as bipole pairs, withleading edges of microelectrodes within a pair separated by a firstdistance ranging between about 1 mm and 3 mm, and with leading edges ofleading microelectrodes between pairs separated by a second distanceranging between 1 mm and 6 mm.
 18. The catheter of claim 17, wherein thefirst distance is about 2 mm and the second distance is about 6 mm.